Levetiracetam Pregnancy Registry: Final results and a review of the impact of registry methodology and definitions on the prevalence of major congenital malformations

Background: To evaluate pregnancy outcomes among women participating in the antiepileptic drug (AED) Levetiracetam Registry (LEV-Registry), and to review the impact of using two other registries' outcome definitions on the number of major congenital malformations (MCMs). Methods: This US-based prospective study (ClinicalTrials.gov NCT00345475) was overseen by an independent Expert Panel. Women exposed to levetiracetam at any time during pregnancy enrolled, directly, or via their healthcare provider. The primary outcome was prevalence of MCMs, defined according to a modified version of the Metropolitan Atlanta Congenital Defects Program criteria. Results: Of 491 women enrolled, 465 (94.7%) had a documented outcome. Most (92.3%) received levetiracetam for epilepsy; 323 (69.4%) as monotherapy and 142 (30.5%) as polytherapy. With three twin pregnancies, there were 468 outcomes—444 livebirths, 3 stillbirths, 19 miscarriages, and 2 terminations. Based on the MCM definition used by LEV-Registry, 46 infants among 444 livebirths had MCMs resulting in 10.4% (95% CI 7.7, 13.6) for overall prevalence, 9.4% (95% CI 6.4, 13.2) with monotherapy, and 12.6% (95% CI 7.5, 19.4) with polytherapy. When MCM reports were reviewed independently by staff at EURAP (International Registry of AEDs) and North American AED Pregnancy Registry according to their respective criteria, only 22 and 7 infants of the 46, respectively, were classified as having MCMs. Conclusion: The LEV-Registry Expert Panel did not find evidence suggestive of teratogenic association with prenatal exposure to levetiracetam. The substantial differences in which physical findings were considered MCMs highlight the major impact of pregnancy registry methodology on MCM prevalence estimates.